A tannin micro-environment confined bimetallic carbon-based catalyst, and a preparation method and application thereof

Abstract

The present application relates to a kind of tannin microenvironment limited bimetallic carbon-based catalyst and its preparation method and application.The zero-valent zinc-containing magnetic carbon nanotube (ZFC) prepared by iron ion modification and zinc powder sintering is solid-phase ground with waxberry tannin foam (TF), the tannin limited microenvironment is constructed in situ on the surface of catalyst, and finally the composite material (ZCF-TF) is prepared.The present application utilizes the high nucleophilic characteristics of polyphenol hydroxyl group of tannin, not only can in-situ capture leached free metal ions in the reaction system to realize "interface reconstruction", solve the problem of secondary pollution of heavy metal;More through the unique surface microenvironment, the local electronic structure of catalyst is changed, the traditional non-selective radical dilemma is successfully avoided, and the Fenton-like catalysis is changed into electron transfer (ETP) and singlet oxygen dominated non-radical path.The catalyst shows precise and efficient degradation ability to antibiotics in water body, and has strong anti-water quality background interference ability.

Description

Technical Field

[0001] This invention relates to the field of water pollution control and environmental catalytic materials technology, and in particular to a tannin-confined microenvironment bimetallic carbon-based catalyst, its preparation method, and its application in antibiotic wastewater treatment. Background Technology

[0002] Traditional homogeneous Fenton technology suffers from bottlenecks such as high H2O2 consumption, a narrow optimal pH window (2-4), and abundant iron sludge. Furthermore, its non-selective bulk free radical pathway is easily quenched by the complex matrix in actual wastewater, resulting in low oxidant utilization. While the Electro-Fenton system can improve energy efficiency, continuous anode dissolution can cause secondary metal pollution. On the other hand, the traditional "passive coating" control strategy easily buries active sites, leading to a significant decrease in catalytic efficiency.

[0003] Therefore, this invention changes the material design concept from "passive resistance" to "active capture and interface reconstruction": by using a highly chelating natural polyphenol framework, dissolved metal ions are dynamically captured and recovered at the solid-liquid interface, and an interfacial catalytic active center is constructed in situ, thereby eliminating metal loss and confining the catalytic reaction to the solid-liquid boundary, achieving highly selective and highly tolerant non-radical catalytic degradation.

[0004] It should be noted that the information disclosed in the background section of this invention is only for enhancing the understanding of the general technical situation in the field to which this invention pertains, and does not constitute any form of acknowledgment or implication of prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to address the challenges of readily lost active metals and susceptibility of bulk radicals to interference from aqueous anions in existing micro-electrolysis advanced oxidation technologies. This invention provides a tannin-confined bimetallic carbon-based catalyst, its preparation method, and its applications. This catalyst achieves active capture of lost metals by constructing a natural tannin network on the surface of a carbon-based bimetallic catalyst, guiding the system towards an efficient non-radical targeted degradation pathway.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing a tannin-confined bimetallic carbon-based catalyst, comprising the following steps: (1) Dissolve ferrous salt and ferric salt in ultrapure water, add ball-milled activated hydroxylated carbon nanotubes, add ammonia water for co-precipitation, and obtain magnetic composite material CNTs-Fe3O4 by magnetic separation, washing and drying. (2) The magnetic composite material is mixed with zinc powder and polyethylene glycol and carbonized at high temperature under nitrogen protection to obtain bimetallic carbon-based material ZFC; (3) Mix, grind and disperse the tannin foam with the bimetallic carbon-based material to obtain the tannin microenvironment confined bimetallic carbon-based catalyst ZFC-TF.

[0007] Preferably, in step (1), the mass-to-volume ratio of ferrous salt, ferric salt, hydroxylated carbon nanotubes, and ultrapure water is 0.4~0.5 g: 0.6~0.8 g: 0.4~0.5 g: 35~45 mL; In step (2), the mass ratio of magnetic composite material, zinc powder and polyethylene glycol is 1:0.8~1.2:2~3.

[0008] Preferably, in step (1), the ferrous salt is FeSO4·7H2O and the ferric salt is FeCl3·6H2O; In step (2), the polyethylene glycol is polyethylene glycol 4000; In step (3), the tannin foam is bayberry tannin foam.

[0009] Preferably, the stirring speed in step (1) is 400~600 rpm and the stirring time is 3~8 min; The mixing temperature in step (2) is 55~65 ℃, and the mixing time is 15~25 min.

[0010] Preferably, the drying temperature in step (1) is 55~65 ℃ and the drying time is 10~14 h; The high-temperature carbonization temperature in step (2) is 450~550 ℃, and the high-temperature carbonization time is 1~3h.

[0011] Preferably, the concentration of ammonia added in step (1) is 1.5~2.5 M, and the number of hydroxyl groups on the surface of the ball-milled activated hydroxylated carbon nanotubes is not less than 800 µmol / g; Preferably, the mass ratio of tannin foam to bimetallic carbon-based material in step (3) is 1:1 to 20:1.

[0012] Preferably, the temperature for dissolving the iron source in step (1) is 35~45 ℃, and the pH adjusted by co-precipitation is above 10.0; The reaction processes in steps (1) to (3) are all carried out under a nitrogen atmosphere.

[0013] The present invention also provides a tannin-confined bimetallic carbon-based catalyst prepared by the above preparation method.

[0014] This invention also provides an application of a tannin-confined microenvironment bimetallic carbon-based catalyst in the catalytic degradation of organic wastewater pollutants.

[0015] The present invention has the following beneficial effects: 1. Excellent ability to capture metal loss and dynamically reconfigure catalytic active sites. This invention abandons the traditional passive coating and control strategy, cleverly utilizing a tannin framework rich in catechol and gallic acid groups as a "dynamic capture platform." This structure can actively capture dissolved zinc and iron ions during micro-electrolysis in real time, achieving extremely high metal recovery rates (86.3% for zinc and 79.4% for iron) under strongly acidic conditions. The captured zinc ions act as Lewis acid centers, regulating the local electronic structure of the tannin substrate and promoting the co-anchoring of H2O2 and pollutants in situ. Simultaneously, the spontaneous capture of iron ions continuously activates the interfacial redox nodes, achieving dynamic self-reconstruction of the catalytic interface.

[0016] 2. Highly selective interface-confined non-radical catalysis mechanism, avoiding bulk side reactions and secondary pollution.

[0017] This invention utilizes the spatial confinement effect of the tannin network to strictly limit the catalytic reaction to the solid-liquid interface. The spontaneous capture of free iron ions by the tannin framework fundamentally prevents the non-selective generation of ·OH ions triggered by free iron in the bulk phase, avoiding the ineffective consumption of the oxidant by the random Fenton reaction in the bulk phase. The system targets the electron transfer pathway (ETP) and singlet oxygen at the interface. 1 O2-induced degradation. Within a wide pH range (3.0–9.0), the system maintains a highly specific non-radical-dominated mechanism, achieving efficient degradation while resolving the contradiction between transition metal leaching and catalytic selectivity. Attached Figure Description

[0018] Figure 1 Scanning electron microscope images of the CNTs-OH, ZFC, TF and ZFC-TF catalysts prepared in Example 1; Figure 2 The elemental distribution of the ZFC-TF catalyst prepared in Example 1 is shown in the scanning electron microscope image. Figure 3 The graph shows a comparison of the degradation performance of the ZFC-TF catalyst prepared in Example 1 and the materials prepared in Comparative Examples 1 and 2 on tetracycline under different initial pH conditions. Figure 4 This is a comparison chart of the performance of the ZFC-TF catalyst prepared in Example 1 in catalytic degradation of tetracycline under different quenching conditions; Figure 5 The graph shows the degradation effect of the ZFC-TF catalyst prepared in Example 1 on four tetracycline antibiotics. Figure 6A comparison of the leaching concentrations of zinc and iron ions in the ZFC-TF catalyst prepared in Example 1 and the ZFC material prepared in Comparative Example 2 under different initial pH conditions. Detailed Implementation

[0019] This invention provides a method for preparing a tannin-confined bimetallic carbon-based catalyst, comprising the following steps: (1) Dissolve ferrous salt and ferric salt in ultrapure water, add ball-milled activated hydroxylated carbon nanotubes, add ammonia water for co-precipitation, and obtain magnetic composite material CNTs-Fe3O4 by magnetic separation, washing and drying. (2) The magnetic composite material is mixed with zinc powder and polyethylene glycol and carbonized at high temperature under nitrogen protection to obtain bimetallic carbon-based material ZFC; (3) Mix, grind and disperse the tannin foam with the bimetallic carbon-based material to obtain the tannin microenvironment confined bimetallic carbon-based catalyst ZFC-TF.

[0020] In this invention, the ferrous salt in step (1) is preferably FeSO4·7H2O, and the ferric salt is preferably FeCl3·6H2O; the polyethylene glycol in step (2) is preferably polyethylene glycol 4000; and the tannin foam in step (3) is preferably bayberry tannin foam.

[0021] In this invention, the mass-to-volume ratio of ferrous salt, ferric salt, hydroxylated carbon nanotubes, and ultrapure water in step (1) is 0.4~0.5 g: 0.6~0.8 g: 0.4~0.5 g: 35~45 mL. More preferably, it is 0.45~0.48 g: 0.68~0.72 g: 0.44~0.48 g: 38~42 mL, and even more preferably, it is 0.48 g: 0.69 g: 0.46 g: 40 mL.

[0022] In this invention, the stirring time after adding hydroxylated carbon nanotubes in step (1) is preferably 3 to 8 min, more preferably 4 to 7 min, and even more preferably 5 min; the stirring time after adding ammonia water for co-precipitation is preferably 20 to 40 min, more preferably 25 to 35 min, and even more preferably 30 min.

[0023] In this invention, the concentration of ammonia water added in step (1) is preferably 1.5~2.5 M, more preferably 1.8~2.2 M, and even more preferably 2.0 M; the ammonia water is added until the pH exceeds 10.0.

[0024] In this invention, the temperature for dissolving ferrous salt and ferric salt in step (1) is preferably 35~45 ℃, more preferably 38~42 ℃, and even more preferably 40 ℃.

[0025] In this invention, the drying temperature in step (1) is preferably 55~65 ℃, more preferably 58~62 ℃, and even more preferably 60 ℃; the drying time is preferably 10~14 h, more preferably 11~13 h, and even more preferably 12 h.

[0026] In this invention, the number of hydroxyl groups on the surface of the ball-milled activated hydroxylated carbon nanotubes is not less than 800 µmol / g.

[0027] In this invention, the mass ratio of magnetic composite material, zinc powder and polyethylene glycol in step (2) is preferably 1:0.8~1.2:2~3, more preferably 1:0.9~1.1:2.2~2.8, and even more preferably 1:1:2.5.

[0028] In this invention, the mixing temperature in step (2) is preferably 55~65 ℃, more preferably 58~62 ℃, and even more preferably 60 ℃; the mixing time is preferably 15~25 min, more preferably 18~22 min, and even more preferably 20 min.

[0029] In this invention, the temperature of high-temperature carbonization in step (2) is preferably 450~550 ℃, more preferably 480~520 ℃, and even more preferably 500 ℃; the time of high-temperature carbonization is preferably 1~3 h, more preferably 1.5~2.5 h, and even more preferably 2 h.

[0030] In this invention, the reaction process in step (2) is carried out under a nitrogen atmosphere.

[0031] In this invention, the mass ratio of tannin foam to bimetallic carbon-based material in step (3) is preferably 1:1 to 20:1, more preferably 5:1 to 15:1, and even more preferably 10:1.

[0032] In this invention, the grinding and dispersion in step (3) is carried out under nitrogen protection until a uniform brown powder is formed.

[0033] The present invention also provides a tannin-confined bimetallic carbon-based catalyst prepared by the above preparation method.

[0034] This invention also provides the application of the tannin-confined bimetallic carbon-based catalyst in the catalytic degradation of tetracycline antibiotics in wastewater.

[0035] In this invention, the specific method of application includes the following steps: adding the catalyst to wastewater containing tetracycline antibiotics, adjusting the pH to 3.0~9.0, placing it in a shaker for oscillation reaction, and completing the antibiotic adsorption.

[0036] In this invention, the amount of catalyst used is preferably 2.0~8.0 g / L, more preferably 4.0~6.0 g / L, and even more preferably 5.5 g / L.

[0037] In this invention, the temperature of the oscillation reaction is 25 °C, and the time of the oscillation reaction is preferably 10~24 h.

[0038] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0039] Example 1 Under N2 protection at 40 °C, 0.48 g FeSO4·7H2O and 0.69 g FeCl3·6H2O were dissolved in 40 mL of ultrapure water. 0.46 g of ball-milled activated hydroxylated carbon nanotubes (CNTs-OH, 850 µmol / g surface hydroxyl groups) were added, and the mixture was stirred for 5 min. 2.0 M ammonia was added dropwise until the pH exceeded 10.0, and stirring continued for 30 min. The mixture was magnetically separated, washed with ultrapure water, and vacuum dried at 60 °C for 12 h to obtain the magnetic composite material CNTs-Fe3O4.

[0040] The above CNTs-Fe3O4, zinc powder and polyethylene glycol 4000 were mixed at a mass ratio of 1:1:2.5 and stirred for 20 min at 60 ℃ under N2 protection. The mixture was then transferred to a tube furnace and carbonized at 500 ℃ for 2 h under N2 flow to obtain bimetallic carbon-based material ZFC.

[0041] Mix bayberry tannin foam (TF) with ZFC at a mass ratio of 10:1, and grind and disperse it thoroughly under N2 protection until it becomes a uniform brown powder, thus obtaining the bimetallic carbon-based catalyst ZFC-TF with tannin microenvironment confinement.

[0042] Example 2 Under N2 protection at 38 °C, 0.45 g FeSO4·7H2O and 0.68 g FeCl3·6H2O were dissolved in 38 mL of ultrapure water. 0.44 g of ball-milled activated hydroxylated carbon nanotubes (CNTs-OH, 820 µmol / g surface hydroxyl groups) were added, and the mixture was stirred for 4 min. 1.8 M ammonia was added dropwise until the pH exceeded 10.0, and stirring continued for 25 min. The mixture was magnetically separated, washed with ultrapure water, and vacuum dried at 58 °C for 11 h to obtain CNTs-Fe3O4.

[0043] The above CNTs-Fe3O4, zinc powder and polyethylene glycol 4000 were mixed at a mass ratio of 1:0.9:2.2 and stirred for 18 min at 58 ℃ under N2 protection. The mixture was then transferred to a tube furnace and carbonized at 480 ℃ for 2.5 h under N2 flow to obtain ZFC.

[0044] The tannin foam (TF) of bayberry and ZFC were mixed at a mass ratio of 5:1 and then thoroughly ground and dispersed into a uniform brown powder under N2 protection to obtain the catalyst.

[0045] Example 3 Under N2 protection at 42 °C, 0.48 g FeSO4·7H2O and 0.72 g FeCl3·6H2O were dissolved in 42 mL of ultrapure water. 0.48 g of ball-milled activated hydroxylated carbon nanotubes (CNTs-OH, 880 µmol / g surface hydroxyl groups) were added, and the mixture was stirred for 7 min. 2.2 M ammonia was added dropwise until the pH exceeded 10.0, and stirring continued for 35 min. The mixture was magnetically separated, washed, and vacuum dried at 62 °C for 13 h to obtain CNTs-Fe3O4.

[0046] The above CNTs-Fe3O4, zinc powder and polyethylene glycol 4000 were mixed at a mass ratio of 1:1.1:2.8 and stirred for 22 min at 62 ℃ under N2 protection. The mixture was then transferred to a tube furnace and carbonized at 550 ℃ for 1.5 h under N2 flow to obtain ZFC.

[0047] Mix bayberry tannin foam (TF) and ZFC at a mass ratio of 15:1, and grind and disperse them thoroughly under N2 protection until a uniform brown powder is obtained to obtain the catalyst.

[0048] Example 4 Under N2 protection at 40 °C, 0.48 g FeSO4·7H2O and 0.69 g FeCl3·6H2O were dissolved in 40 mL of ultrapure water. 0.46 g of ball-milled activated hydroxylated carbon nanotubes (CNTs-OH, 850 µmol / g surface hydroxyl groups) were added, and the mixture was stirred for 5 min. 2.0 M ammonia was added dropwise until the pH exceeded 10.0, and stirring continued for 30 min. The mixture was magnetically separated, washed, and vacuum dried at 60 °C for 12 h to obtain CNTs-Fe3O4.

[0049] The above CNTs-Fe3O4, zinc powder and polyethylene glycol 4000 were mixed at a mass ratio of 1:1:2.5 and stirred for 20 min at 60 ℃ under N2 protection. The mixture was then transferred to a tube furnace and carbonized at 450 ℃ for 3 h under N2 flow to obtain ZFC.

[0050] Mix bayberry tannin foam (TF) and ZFC at a mass ratio of 10:1, and grind and disperse them thoroughly under N2 protection until a uniform brown powder is obtained to obtain the catalyst.

[0051] Example 5 Under N2 protection at 40 °C, 0.48 g FeSO4·7H2O and 0.69 g FeCl3·6H2O were dissolved in 40 mL of ultrapure water. 0.46 g of ball-milled activated hydroxylated carbon nanotubes (CNTs-OH, 850 µmol / g surface hydroxyl groups) were added, and the mixture was stirred for 3 min. 2.0 M ammonia was added dropwise until the pH exceeded 10.0, and stirring continued for 20 min. The mixture was magnetically separated, washed, and vacuum dried at 55 °C for 14 h to obtain CNTs-Fe3O4.

[0052] The above CNTs-Fe3O4, zinc powder and polyethylene glycol 4000 were mixed at a mass ratio of 1:0.8:2.0 and stirred for 15 min at 55 ℃ under N2 protection. The mixture was then transferred to a tube furnace and carbonized at 500 ℃ for 2 h under N2 flow to obtain ZFC.

[0053] Mix bayberry tannin foam (TF) and ZFC at a mass ratio of 20:1, and grind and disperse them thoroughly under N2 protection until a uniform brown powder is obtained to obtain the catalyst.

[0054] Scanning electron microscopy was performed on the CNTs-OH, ZFC, TF, and ZFC-TF catalysts prepared in Example 1, as shown in the figure. Figure 1 As shown.

[0055] from Figure 1 As can be seen, CNTs-OH exhibits a typical disordered orientation and intertwined tubular network structure. With the introduction of Zn... 0 After being combined with Fe3O4, the unique tubular morphology of CNTs was well preserved. The TF support exhibited a unique spherical microstructure. After the introduction of ZFC, the structural integrity of the tannin foam was maintained, and the tubular CNTs and active particles effectively covered the foam surface.

[0056] Figure 2 This is a scanning electron microscope (SEM) image of the iron element distribution of the ZFC-TF catalyst in Example 1.

[0057] from Figure 2 As can be seen, carbon (C), oxygen (O), iron (Fe), and zinc (Zn) are uniformly distributed in the ZFC-TF structure, with no obvious aggregation. This uniform dispersion is mainly attributed to the highly porous nature of the tannin foam material. Its rigid and interconnected pore walls act as a template, contributing to the effective fixation and dispersion of the ZFC composite material.

[0058] Comparative Example 1 20.0 g of bayberry tannin was ultrasonically dissolved in 30 mL of water, followed by stirring at 500 rpm. Then, 1.42 g of urotropine and 0.56 g of p-toluenesulfonic acid were added and stirred for 10 min. Next, 0.43 mL of Tween-80 was added, and the stirring speed was increased to 1200 rpm for a second stirring. Once the tannin foam had fully foamed and its volume no longer changed, it was removed and cured in an oven at 85 ℃ for 24 h. The cured material was ground into powder, sieved, washed successively with water and acetone aqueous solution, filtered, and dried to obtain bayberry tannin foam (TF).

[0059] Comparative Example 2 Under N2 protection at 40 °C, 0.48 g FeSO4·7H2O and 0.69 g FeCl3·6H2O were dissolved in 40 mL of ultrapure water. 0.46 g of ball-milled activated hydroxylated carbon nanotubes (CNTs-OH, 850 µmol / g surface hydroxyl groups) were added, and the mixture was stirred for 5 min. 2.0 M ammonia was added dropwise until the pH exceeded 10.0, and stirring continued for 30 min. The mixture was magnetically separated, washed with ultrapure water, and vacuum dried at 60 °C for 12 h to obtain the magnetic composite material CNTs-Fe3O4.

[0060] The above CNTs-Fe3O4, zinc powder and polyethylene glycol 4000 were mixed at a mass ratio of 1:1:2.5 and stirred for 20 min at 60 ℃ under N2 protection. The mixture was then transferred to a tube furnace and carbonized at 500 ℃ for 2 h under N2 flow to obtain bimetallic carbon-based material ZFC.

[0061] Performance testing: The materials prepared in Example 1 (ZFC-TF), Comparative Example 1 (TF), and Comparative Example 2 (ZFC) were used to remove tetracycline.

[0062] The experimental procedure was as follows: 0.55 g of the prepared catalyst was weighed and added to 100 mL of TC solution (250.0 mg / L). The initial pH was adjusted to the specified value using dilute hydrochloric acid or sodium hydroxide. The reaction was carried out in a constant temperature shaker at 25 ℃ with shaking at 180 rpm for 24 h. Samples were taken at preset time points, filtered through a 0.22 μm filter membrane, and the residual concentration of tetracycline was determined by high performance liquid chromatography (HPLC). The degradation efficiency was calculated. When investigating the effect of initial pH, the pH was adjusted to 1.0–11.0, and the results are as follows. Figure 3 As shown.

[0063] from Figure 3As can be seen, the degradation performance of the three materials differs significantly under different initial pH conditions. Within the pH range of 3.0–9.0, ZFC-TF consistently maintains a degradation rate above 85%; while the degradation rate of ZFC decreases significantly under alkaline conditions (pH ≥ 9), and TF exhibits a low removal rate throughout the test conditions. This indicates that the composite of tannin foam broadens the pH adaptability range of the catalyst and effectively maintains high degradation efficiency over a wide pH range.

[0064] Using ZFC-TF as a catalyst, the effects of different quenchers on the degradation reaction were investigated by adding 100 mM tert-butanol (TBA), 100 mM methanol (MeOH), 10 mM p-benzoquinone (p-BQ), 10 mM L-histidine (L-His), 1 mM methyl phenyl sulfoxide (PMSO), or 1 mM potassium ferricyanide (K3[Fe(CN)6]) to the tetracycline solution, respectively. The results are as follows: Figure 4 As shown.

[0065] from Figure 4 As can be seen from the data, the addition of ·OH quenchers TBA, MeOH, and ·O2... - After adding the quencher p-BQ, the degradation efficiency of TC showed no significant change; the addition of the high-valent iron active species probe PMSO also had no significant inhibition. However, the degradation rate decreased by 28.9% after adding the electron trap K3[Fe(CN)6]. 1 The O2 quencher L-His reduced the catalytic activity by 16.3%. This confirms that the main catalytic mechanism of this system is the electron transfer pathway (ETP), supplemented by singlet oxygen (…). 1 The contribution of O2).

[0066] The ZFC-TF catalyst prepared in Example 1 was used to degrade different types of tetracycline antibiotics, including tetracycline (TC), oxytetracycline (OTC), chlortetracycline (CTC), and minocycline hydrochloride (MNC). The results are as follows: Figure 5 As shown.

[0067] from Figure 5 As can be seen, under pH conditions of 3.0-9.0, ZFC-TF achieved a degradation rate of over 85% for TC, OTC, and MNC, and a degradation rate of over 69% for CTC, indicating that the catalyst has a broad-spectrum degradation ability for tetracycline antibiotics.

[0068] When comparing the metal ion recovery performance of ZFC and ZFC-TF at different pH levels, the leaching concentrations of zinc and iron ions in the ZFC and ZFC-TF systems were compared, and the results are as follows: Figure 6 As shown.

[0069] from Figure 6As can be seen, the leaching concentrations of zinc and iron in the ZFC-TF system are significantly lower than those in the ZFC system. At pH 3.0, the metal recovery rate is extremely high (86.3% for zinc and 79.4% for iron). This indicates that tannin foam has a highly efficient active capture capability for metal ions, effectively suppressing secondary pollution by recovering lost metal species in real time through electrostatic attraction and chelation.

[0070] As shown in the above embodiments, this invention provides a method for preparing a tannin-confined bimetallic carbon-based catalyst and its application in the degradation of tetracycline antibiotics in wastewater. This method uses bayberry tannin foam as a confined microenvironment. By combining it with a bimetallic carbon-based material (ZFC), a tannin-confined microenvironment is constructed on the catalyst surface, achieving active capture of dissolved metal ions and interfacial catalytic reactions. The tannin skeleton is rich in catechol groups, which can capture dissolved zinc and iron ions in real time during micro-electrolysis through electrostatic attraction and chelation, fundamentally eliminating homogeneous Fenton side reactions initiated by free metal ions. This confines the catalytic reaction to the solid-liquid interface, enabling efficient degradation of antibiotics via a non-radical pathway.

[0071] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a tannin-confined bimetallic carbon-based catalyst, characterized in that, Includes the following steps: (1) Dissolve ferrous salt and ferric salt in ultrapure water, add ball-milled activated hydroxylated carbon nanotubes, add ammonia water for co-precipitation, and obtain magnetic composite material CNTs-Fe3O4 by magnetic separation, washing and drying. (2) The magnetic composite material is mixed with zinc powder and polyethylene glycol and carbonized at high temperature under nitrogen protection to obtain bimetallic carbon-based material ZFC; (3) Mix, grind and disperse the tannin foam with the bimetallic carbon-based material to obtain the tannin microenvironment confined bimetallic carbon-based catalyst ZFC-TF.

2. The preparation method according to claim 1, characterized in that, In step (1), the mass-to-volume ratio of ferrous salt, ferric salt, hydroxylated carbon nanotubes, and ultrapure water is 0.4~0.5 g: 0.6~0.8 g: 0.4~0.5 g: 35~45 mL; In step (2), the mass ratio of magnetic composite material, zinc powder and polyethylene glycol is 1:0.8~1.2:2~3; In step (3), the mass ratio of tannin foam to bimetallic carbon-based material is 1:1 to 20:

1.

3. The preparation method according to claim 1, characterized in that, In step (1), the ferrous salt is FeSO4·7H2O and the ferric salt is FeCl3·6H2O; In step (2), the polyethylene glycol is polyethylene glycol 4000; In step (3), the tannin foam is bayberry tannin foam.

4. The preparation method according to claim 1, characterized in that, The stirring time after adding hydroxylated carbon nanotubes in step (1) is 3-8 min, and the stirring time after adding ammonia water for co-precipitation is 20-40 min. The mixing temperature in step (2) is 55~65 ℃, and the mixing time is 15~25 min.

5. The preparation method according to claim 1, characterized in that, The drying temperature in step (1) is 55~65℃ and the drying time is 10~14 h; In step (2), the high-temperature carbonization temperature is 450~550 ℃ and the high-temperature carbonization time is 1~3 h.

6. The preparation method according to claim 1, characterized in that, The concentration of ammonia added in step (1) is 1.5~2.5 M, and the number of hydroxyl groups on the surface of the ball-milled activated hydroxylated carbon nanotubes is not less than 800 µmol / g.

7. The preparation method according to claim 1, characterized in that, In step (2), the temperature for dissolving the iron source is 35~45 ℃, and the pH adjusted by co-precipitation is above 10.0; The reaction processes in steps (1) to (3) are all carried out under a nitrogen atmosphere.

8. A tannin-confined bimetallic carbon-based catalyst for antibiotic wastewater degradation prepared by the method described in any one of claims 1 to 8.

9. The application of the tannin-confined bimetallic carbon-based catalyst of claim 9 in the catalytic degradation of tetracycline antibiotics in wastewater.

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